X-ray CCD for spectroscopy and polarization in space

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The present decade is opening new frontiers in high energy astrophysics. After the X-ray satellites in the 1980's, several satellites are or will soon be simultaneously in orbit offering spectacular advances in X-ray imaging at low energiesm, as well as at high energies, in spectroscopy with increased bandwidth , and in timing. These allow us to study X-ray atomic radiation from hot plasmas (thermal X-rays) and/or high energy electrons (non-thermal X-rays). The key issue is how to separately observe the thermal and non-thermal X-rays. One typical example is found with ASCA.We discovered synchrotron X-ray emission emitted by very high energy charged particles in some supernova remnants. Subsequent observations by a Cherenkov telescope, CANGAROO, detected very high energy gamma-rays in the TeV range from one of the supernova remnants. These discoveries are clear evidences for the shock waves of the supernova remnants to be the origin of the cosmic rays.For further development to separate … More ly observe the thermal and non-thermal X-rays , we have planed to develop the technology of direct detection of X-ray polaization, coupled with imaging and spectroscopic capabilities. We have already demonstrated that a small pixel size CCD has these potentialities. We thus intended to develop small pixel size and thick depletion layer CCDs. The second requirement is also essential, because non-thermal X-rays are usually extending up to high energies.The items and results of our study are ;(1) We have made thick layer CCDs and developed the signal processing method to reduce the read-out noises.(2) We are developing 8-micron pixel CCDs to increase analizing power for the polarized X-rays(3) Since small pixel CCDs require high read-out logic, we have developed this technology(4) All above technologies are space-qualified by many environmental tests. In particular, we have studied and developed the radiation-damage-in-space and its restoration technique.(5) In parallel with these technology innovations, we have made many astrophysical studies using X-ray CCDs onboard the ASCA satellite. Less